Question: What is the result of running the following program?
1 import java.util.*;
2 interface A {}
3 class B implements A {}
4 class C implements A {}
5 public class Boxes {
6 private static int countBoxes(List<A> list) {return list.size();}
7 private static int countBoxes2(List<? extends A> list) { return list.size();}
8 public static void main(String[] args) {
9 List<B> b = new ArrayList<>();
10 b.add(new B());
11 List<C> cs = new ArrayList<>();
12 cs.add(new C());
13
14 List<A> a = new ArrayList<>();
15 a.addAll(b);
16 a.addAll(cs);
17
18 System.out.print(countBoxes(b));
19 System.out.print(countBoxes(cs));
20 System.out.print(countBoxes(a));
21
22 System.out.print(countBoxes2(b));
23 System.out.print(countBoxes2(cs));
24 System.out.print(countBoxes2(a));
25 }}
Choice:
A. 112112
B. 112
C. 1
D. 11211
E. code throw exceptions at runtime
F. compiler error at line 7
G. compiler error at line 18
H. compiler error at line 19
